ITU-R BS.1170-2 notably defines LU (Loudness</link> Unit) and LUFS (Loudness</link> Unit, referenced to Full Scale</link>) units, which are used by EBU R128, and Maximum True Peak</link> Level</link>.
LU is used for measurements relative to a reference level and measuring range.
LUFS is used for absolute measurements.
The meter display is switchable between LUFS (absolute, default) and LU (relative). The target loudness level to aim for is -23 LUFS = 0 LU.
EBU mode specifies three time scales corresponding to three different, complementary loudness levels
Loudness is a measure of global loudness, so individual channel metering is not relevant in this context. No additional slowdown of the attack or release of the meter is employed, as indicated by the norm.
The integrated loudness can be understood as the overload loudness of the audio over time, excluding very soft passages through the use of absolute and relative gating.
Loudness</link> range measures the average long-term variations of the loudness; it is expressed in LU.
EBU R128 specifies two normalized scales: